Fundamentals of Database Systems PDF

Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe  CHAPTER 1 Databases and Database Users Slide 1- 2 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe OUTLINE ◼ Types of Databases and Da...

Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe  CHAPTER 1 Databases and Database Users Slide 1- 2 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe OUTLINE ◼ Types of Databases and Database Applications ◼ Basic Definitions ◼ Typical DBMS Functionality ◼ Example of a Database (UNIVERSITY) ◼ Main Characteristics of the Database Approach ◼ Types of Database Users ◼ Advantages of Using the Database Approach ◼ When Not to Use Databases Slide 1- 3 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe What is data, database, DBMS ◼ Data: Known facts that can be recorded and have an implicit meaning; raw ◼ Database: a highly organized, interrelated, and structured set of data about a particular enterprise ◼ Controlled by a database management system (DBMS) ◼ DBMS ◼ Set of programs to access the data ◼ Database systems are used to manage collections of data that are: ◼ Highly valuable ◼ Relatively large ◼ Accessed by multiple users and applications, often at the same time. ◼ A modern database system is a complex software system whose task is to manage a large, complex collection of data. ◼ Databases touch all aspects of our lives. Slide 1- 4 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Basic Definitions ◼ Database: ◼ A collection of related data. ◼ Data: ◼ Known facts that can be recorded and have an implicit meaning. ◼ Mini-world: ◼ Some part of the real world about which data is stored in a database. For example, student grades and transcripts at a university. ◼ Database Management System (DBMS): ◼ A software package/system to facilitate the creation and maintenance of a computerized database. ◼ Database system: ◼ The DBMS software together with the data itself. Sometimes, the applications are also included. Slide 1- 5 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Types of Databases and Database Applications ◼ Traditional applications: ◼ Numeric and textual databases ◼ More recent applications: ◼ Multimedia databases ◼ Geographic Information Systems (GIS) ◼ Biological and genome databases ◼ Mobile databases ◼ Real-time and active databases Slide 1- 6 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Lifecycle of Data: 4 “A”s Acquisition Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe File Based System Slide 1- 8 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe File Based System - Example Slide 1- 9 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Limitation of File based approach Slide 1- 10 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Definitions(1) Slide 1- 11 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Definitions(2)- Data Vs. Information Slide 1- 12 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Definitions(3) Slide 1- 13 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Data and Metadata example Slide 1- 14 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe  Definitions(4) ◼ Mini-world: ◼ Some part of the real world about which data is stored in a database. For example, student grades and transcripts at a university. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 15 Definitions(5) Slide 1- 16 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe A simplified architecture for a database system Slide 1- 17 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Example Slide 1- 18 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe What a DBMS Facilitates (Functionality) ◼ Manipulating the database: ◼ Retrieval: Querying, generating reports ◼ Modification: Insertions, deletions and updates to its content ◼ Accessing the database through Web applications ◼ Processing and sharing by a set of concurrent users and application programs – yet, keeping all data valid and consistent. Slide 1- 19 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Application Programs and DBMS ◼ Applications interact with a database by generating - Queries: that access different parts of data and formulate the result of a request - Transactions: that may read some data and “update” certain values or generate new data and store that in the database ◼ Applications must not allow unauthorized users to access data ◼ Applications must keep up with changing user requirements against the database Slide 1- 20 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Additional DBMS Functionality ◼ DBMS may additionally provide: ◼ Protection or Security measures to prevent unauthorized access ◼ “Active” processing to take internal actions on data ◼ Presentation and Visualization of data ◼ Maintenance of the database and associated programs over the lifetime of the database application ◼ Called database, software, and system maintenance Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 21 Example of a Database (with a Conceptual Data Model) ◼ Mini-world for the example: ◼ Part of a UNIVERSITY environment ◼ Some mini-world entities: ◼ STUDENTs ◼ COURSEs ◼ SECTIONs (of COURSEs) ◼ (Academic) DEPARTMENTs ◼ INSTRUCTORs Slide 1- 22 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Example of a Database (with a Conceptual Data Model) ◼ Some mini-world relationships: ◼ SECTIONs are of specific COURSEs ◼ STUDENTs take SECTIONs ◼ COURSEs have prerequisite COURSEs ◼ INSTRUCTORs teach SECTIONs ◼ COURSEs are offered by DEPARTMENTs ◼ STUDENTs major in DEPARTMENTs ◼ Note: The above entities and relationships are typically expressed in a conceptual data model, such as the entity-relationship (ER) data or UML class model (see Chapters 3, 4) Slide 1- 23 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Example of a Simple Database Slide 1- 24 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe The relational model Slide 1- 25 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Main Characteristics of the Database Approach ◼ Self-describing nature of a database system: ◼ A DBMS catalog stores the description of a particular database (e.g. data structures, types, and constraints) ◼ The description is called meta-data*. ◼ This allows the DBMS software to work with different database applications. ◼ Insulation between programs and data: ◼ Called program-data independence. ◼ Allows changing data structures and storage organization without having to change the DBMS access programs Slide 1- 26 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Main Characteristics of the Database Approach (continued) ◼ Data abstraction: ◼ A data model is used to hide storage details and present the users with a conceptual view of the database. ◼ Programs refer to the data model constructs rather than data storage details ◼ Support of multiple views of the data: ◼ Each user may see a different view of the database, which describes only the data of interest to that user. Slide 1- 27 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Main Characteristics of the Database Approach (continued) ◼ Sharing of data and multi-user transaction processing: ◼ Allowing a set of concurrent users to retrieve from and to update the database. Slide 1- 28 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Example of a Simplified Database Catalog Slide 1- 29 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Database Users – Actors on the Scene ◼ Actors on the scene ◼ System Analyst: ◼ Determine the user requirements and develop the system specifications. ◼ Database Designers: ◼ Responsible to define the content, the structure, the constraints, and functions or transactions against the database. ◼ Implement the specifications developed by analysts and test and debug them before deployment. ◼ Application programmers: ◼ Implement the specifications developed by analysts and test and debug them before deployment. Slide 1- 30 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Database End Users ◼ Database administrators ◼ Responsible for authorizing access to the database. ◼ Coordinating and monitoring the DB use. ◼ Acquiring software and hardware resources. ◼ Monitoring efficiency of operations. ◼ End-users: They use the data for queries, reports and some of them update the database content. Slide 1- 31 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Advantages of Using the Database Approach(1) Slide 1- 32 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Advantages of Using the Database Approach(2) Slide 1- 33 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Advantages of Using the Database Approach ◼ Providing optimization of queries for efficient processing. ◼ Providing multiple interfaces to different classes of users. ◼ Representing complex relationships among data. ◼ Flexibility to change data structures. ◼ Availability of current information. Slide 1- 34 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe When not to use a DBMS ◼ Main inhibitors (costs) of using a DBMS: ◼ High initial investment and possible need for additional hardware ◼ Overhead for providing generality, security, concurrency control, recovery, and integrity functions ◼ When a DBMS may be unnecessary: ◼ If the database and applications are simple, well defined, and not expected to change ◼ If access to data by multiple users is not required ◼ When a DBMS may be infeasible ◼ In embedded systems where a general-purpose DBMS may not fit in available storage. Slide 1- 35 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Chapter Summary ◼ Types of databases and database applications ◼ Basic definitions ◼ Typical DBMS functionality ◼ Example of a database (UNIVERSITY) ◼ Main characteristics of the database Approach ◼ Types of database users ◼ Advantages of using the database approach ◼ When not to use databases Slide 1- 36 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe